AQY Beyond Expectations: Hydrogen Radical-Enabled Photosynthesis of H<sub>2</sub>O<sub>2</sub> under Mild Conditions
Qi Miao, Meng Liu, Yao-yao Mou, Yifei Zhang, Qing Li, Zi-jie Cao, Wei Jiang
Abstract
In this study, a promising high-efficiency H 2 O 2 photosynthesis process using diphenylmethanol (DPM) as the substrate is reported to improve the practicality of attractive sunlight-driven catalyst-free H 2 O 2 production. The acquired H 2 O 2 yield reaches 109.57 mM·h –1 with an unexpected apparent quantum yield (AQY) of 56.62% at 20 °C, and sharply increases to 194.64 mM·h –1 with increasing AQY of 242.37% at 60 °C, which is close to that of the current anthraquinone method in the industry. Using the mixture system of DPM and 1-phenylethanol, the final H 2 O 2 output concentration is 6386 mM, equivalent to 21.71 wt %. Such a process with industrial prospects is confirmed to be based on a newly found hydrogen radical mechanism rather than traditional hydrogen abstraction by oxygen. Direct homolysis of the benzylic C–H bond occurs under ultraviolet (UV) light irradiation and enables H 2 O 2 generation after reacting with oxygen. The two benzene ring groups of DPM promote the reactivity of the benzylic C–H bond through an electron-withdrawing effect, and the product, benzophenone, enhances the photoreaction dynamics by its autocatalytic effect. These findings highlight the tremendous potential of catalyst-free H 2 O 2 photosynthesis, offering a new pathway for sustainable green H 2 O 2 production.